This invention is directed to method and apparatus for the handling and deforming of relatively short stock such as bars, rods, rounds, pipe, etc., (all of which may be referred to as "short work pieces") in apparatus which is initially designed to handle relatively long stock or workpieces. Preferred embodiments of the invention are particularly adapted for use in conjunction with the upsetting of pipe ends for the making of threaded joints and most particularly in conjunction with the fabrication of oil well casing pup joints, with which the invention will be described.
A pup joint is the name known in the art for a relatively short length of pipe needed, in addition to the regular lengths or strings, to attain the spacing requirement for a wellhead depth.
In the pipe art, as related to oil well casing, it is the practice to upset the pipe ends in order to increase the wall thicknesses thereof in preparation for the thread cutting of pin or box ends of pipe joints. The upsetting is conducted in an upsetting machine comprising a pair of dies, each of which defines a semi-circular cavity for receiving the pipe. In order to upset or swage a pipe end it must first be heated to swaging temperature. This is usually done by conveying the pipe along a path such that the end to be forming by upsetting is conducted through a reheat furnace and then directly to the upsetting machine. The transport means for transporting the pipe through and from the reheat furnace to the upsetting machine is adapted to handle relatively long pipe, i.e., 16 feet and longer, the shortest length in the Range 1 of the API specification for casing. In one known installation, considered to be typical, a series of four rails are provided to serve as the transport means; three of the rails are on eight feet centers with the rail nearest the machine being about six feet--six inches from the next adjacent rail and about nine feet--six inches from the face of the dies of the upsetting machine. Therefore, pipe lengths under ten feet in length require special handling. Tubing or other relatively light pipe members can be handled manually; however, casing, which is relatively heavy, can not be easily handled. Consequently, relatively short lengths of casings which are upset at both ends, such as pup-joints, are not handled or processed in the same manner as are the longer lengths.
It has not been possible to upset both ends of a pup joint in heretofore known existing upsetting machines because the dies could not accommodate an existing upset end while the opposite end is being upset. Heretofore, pup joints with increased wall thickness at the threaded ends have been fabricated by machining a solid round bar, or an extra-heavy wall pipe, having an outside diameter corresponding to outside diameter of the desired upset portion. It becomes apparent that such machining is not only wasteful of stock material but also time consuming and expensive. Also, because of the machinery requirements it is not always possible to fabricate such pup joints from compositions having the same chemistries as the compositions from which the regular pipes are fabricated. The maintenance of chemical homogeneity through a pipe string is important in wells where the string is exposed to hydrogen sulfide.